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Other Support Articles


D118, D119, D120

If this is happening, the input isn’t configured to read a temperature sensor.

The temperature sensor has been disconnected or has broken wires.

The sensor may be affected by a source of ambient heat (e.g. direct sunlight, heat duct proximity). The sensor may also require calibration.

The recognition time setting may be too long. If the unit is not recognizing power failure the batteries may be low.

The programmed recognition time is too short. AC power is subject to brief interruptions which is triggering the response.

If brand new, they will last up to 24 hours.

“Rings Until Answer” is incorrectly programmed for the unit. Models D118/119 may also be connected to an incompatible line.

The local voice mute feature is in effect.

The voice rep is set to zero. Change it to one or greater to correct this problem.

The unit’s number of “Rings Until Answer” is equal to the number of rings that are set for the telephone answering device.

The telephone number may be incorrectly programmed. Tone or Pulse (the current dialing method) is not compatible with the telephone line on which the D118/D119 is installed. The recognition time is too long.

An alert condition does not remain in effect long enough to become a valid alarm. The max number of calls is set to zero. It’s a best practice to set your max calls to at least equal the number of dial-out telephone numbers programmed. The unit must be connected to a standard (2-wire analog) telephone line, not a digital extension to a phone system. If the unit will not dial out and the factors previously listed have been ruled out, try connecting the unit to standard residential telephone line.

TC200, TH300

If the unit is reading LOW in a high humidity environment, let the unit stabilize, this could possible be due to insufficient air flow.

Voltage mode: 1 Meg    Current mode: 250 ohm

Unit may be locked up. Remove and replace the battery for a few minutes or replace with new batteries.

If you have no power, try replacing the batteries.


If there is no display, make sure the battery is good and installed properly.

An icon will appear on the LCD display.

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